This study reports results of petrographical and geochemical analyses on grinding stones (and fragments of grinding stones and other stone stools) from the archaeological site Üllő 5 (Pest County, Hungary). Üllő 5. is the largest excavated Sarmatian site: cca. 9000 object on 300000 m2 from the third-fourth century. Altogether 4133 finds (all made of stone) were surveyed macroscopically, among them 926 grinding stones, millstones, fragments of grinding stones and grinders. Most of them (848 pieces) are made from basaltic andesite. The present paper reports the investigation of the 848 basaltic andesite finds. After the macroscopical observation of the finds; they were grouped and the characteristic samples were further investigated in thin section by polarisation microscopy. Additional chemical analyses have been performed. Bulk chemical analysis was performed with ICP-ES, ICP-MS and with Prompt Gamma Activation Analysis (PGAA); some samples were analysed with electron microprobe analysis (EPMA). (Table 1.)

To get more information about the provenance of the archaeological finds we gathered and studied andesite samples from natural outcrops of the neighbouring volcanic mountains (Börzsöny, Cserhát, Mátra and Karancs Mts.). (Table 1., Fig. 1.) The data were compared with data of analyses found in literature consulted. Most of the investigated grinding stones are made of andesite. Among them two major macroscopic groups could be separated. The microscopic features of the two andesite-types are almost the same. Additional chemical analyses have been performed (ICP-ES, ICP-MS, PGAA and EPMA). On the basis of the analyses of the archaeological finds and our gathered comparative samples [i.e. macroscopical, microscopical and chemical examinations] the basaltic andesite raw materials are originated from the Cserhát Mts.